For tubular textile products such as those mentioned, it is advantageous to provide an inspection stage in conjunction with fabrication, generally prior to conditioning of the fabricated product.
This inspection is most commonly carried out visually after the article has been placed upon a form permitting the article to be spread out or drawn transversely in front of an illuminated plate or table such as a light box so that the article is transluminated and it is possible for an inspector to detect the presence of any flaws.
Various means have been utilized heretofore for placing the article on the form, for effecting a transverse spread of the article by transverse displacement of the form and for release of the article after it has been inspected.
In order to illustrate one approach used in the prior art, especially in an apparatus for the inspection of pantyhose or tights, the form is constituted by two pairs of parallel rods, each pair comprising a fixed rod and a transversely movable rod. The pantyhose are placed over this form and the two movable rods are then displaced to spread the article, permitting visual inspection in the manner described. After inspection, the movable rods are returned to their original positions and the article is ejected by a jet of compressed air directed into the article.
The ability to process a large number of articles at a high rate is poor because of the need to draw the pantyhose completely over the rods on mounting the article on the form.
German patent document No. 1,410,870 describes an inspection apparatus in which an air curtain under pressure is provided to draw the article downwardly over the form for inspection in a similar manner. While the output of such an apparatus is greatly improved because of the automatic threading of the article over the bars of the form by the air curtain directed obliquely downwardly and because a downward movement permits more rapid placing of the article on the form, this apparatus has the disadvantage that the downward movement of the article over the form cannot avoid the formation of pockets in the tubular portions or stockings which may be inspected. As a result, stockings may not be completely stretched or leg portions of pantyhose may not be completely stretched so that rigorous inspection cannot be ensured.